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Developing the TiO 2 /SiO 2 mixed films for low optical loss dielectric mirror --- A retrospect

Developing the TiO 2 /SiO 2 mixed films for low optical loss dielectric mirror --- A retrospect. Prof. Shiuh Chao Institute of Photonics Technologies National Tsing Hua University Taiwan, R.O.C. LIGO-G1000746. R eflection. S cattering. A bsorption. T ransmittion. 1=R+T+S+A

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Developing the TiO 2 /SiO 2 mixed films for low optical loss dielectric mirror --- A retrospect

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  1. Developing the TiO2/SiO2 mixed films for low optical loss dielectric mirror --- A retrospect Prof. Shiuh Chao Institute of Photonics Technologies National Tsing Hua University Taiwan, R.O.C. LIGO-G1000746 Prof. Chao, National Tsing Hua Univ., Taiwan

  2. Reflection Scattering Absorption Transmittion 1=R+T+S+A Total Loss ≡ 1-R-T = S+A Prof. Chao, National Tsing Hua Univ., Taiwan

  3. 曲面鏡 陽極充氣管 陽極 增益氣體 抖動器 腔長控制器 合成稜鏡 陰極 順時針光束 逆時針光束 干涉條紋圖形 光腔長度偵測器 數位訊號輸出 光學共振腔 High Q resonator  low optical loss for the mirrors 陀螺儀 輸出訊號 薄膜鏡 RING LASER GYROSCOPE 光接收器 輸入訊號 逆時針光束 干涉條紋圖 Prof. Chao, National Tsing Hua Univ., Taiwan

  4. Ψ output frequency To avoid lock-in effect => low back-scatter mirror is critical Ω input rate ΩL LOCK-IN EFFECT IN RLG Prof. Chao, National Tsing Hua Univ., Taiwan

  5. H L H nd = 1/2 λ Multi-layer dielectric mirror L H H: TIO2, TA2O5 L: SIO2 Substrate Prof. Chao, National Tsing Hua Univ., Taiwan

  6. Coating Apparatus Ion Beam Sputtering --- dense film --- higher refractive index Prof. Chao, National Tsing Hua Univ., Taiwan

  7. Prof. Chao, National Tsing Hua Univ., Taiwan

  8. Instrumental analysis for mirror characterization Optical constants and thickness: Spectrophotometer Surface roughness: Atomic Force Microscope Structure:X-Ray Diffractometer Total loss: Cavity ring-down lossmeter Optical Microscope Optical Damage: Nd:YAG Laser Chemical bonding: Electron Spectroscopy for Chemical Analysis(ESCA) Concentration: Rutherford Backscattering Spectrometer Prof. Chao, National Tsing Hua Univ., Taiwan

  9. Single TiO2 film Annealing effect on ion-beam-sputtered titanium dioxide filmWen-Hsiang Wang and Shiuh ChaoDepartment of Electrical Engineering, National Tsing Hua University, Hsin-Chu, Taiwan September 15, 1998 / Vol. 23, No. 18 / OPTICS LETTERS 1417 Prof. Chao, National Tsing Hua Univ., Taiwan

  10. Anatase A(101) Prof. Chao, National Tsing Hua Univ., Taiwan

  11. (A) as-deposited (B) annealed 200 oC Prof. Chao, National Tsing Hua Univ., Taiwan

  12. (C) annealed 225 oC (D) annealed 300oC Prof. Chao, National Tsing Hua Univ., Taiwan

  13. Prof. Chao, National Tsing Hua Univ., Taiwan

  14. Prof. Chao, National Tsing Hua Univ., Taiwan

  15. Substrate roughness=> (1) GOOD POLISHING=> REDUCE SUBSTRATE ROUGHNESS(2) RAISE UP THE CRYSTALLIZATION TEMPERATURE OF THE FILM

  16. Single TiO2-SiO2 mixed film Characteristics of ion-beam-sputtered high refractive-index TiO2-SiO2 mixed filmsShiuh Chao and Wen-Hsiang WangDepartment of Electrical Engineering, National Tsing Hua University, Hsin-Chu, TaiwanMin-Yu Hsu and Liang-Chu WangChung-Shan Institute of Science and Technology, Tao-Yuan, TaiwanVol. 16, No. 6/June 1999/J. Opt. Soc. Am. A 1477 Prof. Chao, National Tsing Hua Univ., Taiwan

  17. 5% SiO2 Prof. Chao, National Tsing Hua Univ., Taiwan - 65-

  18. 9% SiO2 Prof. Chao, National Tsing Hua Univ., Taiwan - 66-

  19. 17% SiO2 Prof. Chao, National Tsing Hua Univ., Taiwan - 67-

  20. Prof. Chao, National Tsing Hua Univ., Taiwan

  21. Prof. Chao, National Tsing Hua Univ., Taiwan

  22. (A) SiO2: 0% annealed 300oC (B) SiO2: 17% annealed 300oC Prof. Chao, National Tsing Hua Univ., Taiwan

  23. Prof. Chao, National Tsing Hua Univ., Taiwan

  24. “phase diagram” of the mixed film Prof. Chao, National Tsing Hua Univ., Taiwan 圖(二十八) TiO2-SiO2光學混合膜的退火相圖 -84-

  25. Multi-layer dielectric mirror with the mixed film Low-loss dielectric mirror withion-beam-sputtered TiO2–SiO2 mixed filmsShiuh Chao, Wen-Hsiang Wang, and Cheng-Chung Lee1 May 2001 y Vol. 40, No. 13 y APPLIED OPTICS 2177 Prof. Chao, National Tsing Hua Univ., Taiwan

  26. TiO2+ SiO2 17% SiO2 nd = 1/4 λ TiO2+ SiO2 17% nd = 1/4 λ SiO2 TiO2+ SiO2 17% Zerodur Prof. Chao, National Tsing Hua Univ., Taiwan

  27. Prof. Chao, National Tsing Hua Univ., Taiwan

  28. 0 Total Loss Change (%) Total Loss Change (%) ▲ SiO2 : 0% ● SiO2 : 17 % - 34% 0 - 50 - 50 -100 deposition temp.(820C) -100 Annealing Temperature (0C) Prof. Chao, National Tsing Hua Univ., Taiwan

  29. Laser Induced Damage (A) (B) 3 mm 1.5 mm SiO2:0% as-deposited damage threshold: 2.8 KJ/cm2 (A) (B): damaged spot under optical microscope Prof. Chao, National Tsing Hua Univ., Taiwan

  30. (C) (D) SiO2:0% as-deposited damage threshold: 2.8 KJ/cm2 (C) )(D) damaged spot under AFM Prof. Chao, National Tsing Hua Univ., Taiwan

  31. (A) (B) 3 mm SiO2: 17% annealed 200oC Damage threshold: >6.37 KJ/cm2 (A) Optical microscope (B) AFM of the exposed spot => no damage Prof. Chao, National Tsing Hua Univ., Taiwan

  32. (A) Depth profile for the mirrors (A) as-deposited(B) after 400oC annealing (17% mixing) (Tracing the Ti2p Si2p and O1s by ESCA) Prof. Chao, National Tsing Hua Univ., Taiwan (B)

  33. Prof. Chao, National Tsing Hua Univ., Taiwan

  34. (A) as-deposited 2000C 3000C 4000C (B) well-defined as-deposited 4000C • 圖(三十五)以TiO2-SiO2(17%)混合膜為高折射係數層的雷射反射鏡退火後 的穿透光譜(A)為從光譜儀得到的量測值(B)為從ESCA對鏡片膜層原子分佈的偵測，以薄膜矩陣電腦模擬分析穿透率的結果 Prof. Chao, National Tsing Hua Univ., Taiwan -107-

  35. Other methods for depositing mixed filmsTiO 2-S102 mixed films prepared by the fast alternating sputter method Shiuh Chao, Cheng-Kuel Chang, and Jyh-Shin Chen We introduced the fast alternating sputter method and its application on deposition of TiO2-SiO2 mixedfilms. By using fast alternating sputter, the TiO2 and SiO2 were completely mixed in the film, and no thinpairstructure could be found by x-ray diffraction. The structure of the mixed films was amorphous in a widecomposition range. The optical properties of the mixed films in the visible and near infrared changed fromSiO2-dominant to TiO 2 -dominant as TiO2 content in the film increased. 1 August 1991 / Vol. 30, No. 22 / APPLIED OPTICS 3233 Slow alternating sputter for “nano-film” ? Prof. Chao, National Tsing Hua Univ., Taiwan

  36. Mixed films of TiO2–SiO2 depositedby double electron-beam coevaporationJyh-Shin Chen, Shiuh Chao, Jiann-Shiun Kao, Huan Niu, and Chih-Hsin ChenWe used double electron-beam coevaporation to fabricate TiO2–SiO2 mixed films. The depositionprocess included oxygen partial pressure, substrate temperature, and deposition rate, all of whichwerereal-time computer controlled. The optical properties of the mixed films varied from pure SiO2 to pureTiO2 as the composition of the films varied accordingly. X-ray diffraction showed that the mixed filmsall have amorphous structure with a SiO2 content of as low as 11%. Atomic force microscopy showedthat the mixed film has a smoother surface than pure TiO2 film because of its amorphous structure.Linear and Bruggeman’s effective medium approximation models fit the experimental data betterthan other models.APPLIED OPTICS Vol. 35, No. 1, 90, 1 January 1996 Prof. Chao, National Tsing Hua Univ., Taiwan

  37. Mixed film for LIGO application • One more factor ---- mechanical loss ---- should be added for investigation • Near future: systematically characterizing the mechanical loss of the films • Current effort: recovering the old coating conditions for the films Prof. Chao, National Tsing Hua Univ., Taiwan

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